As oil and gas recovery becomes more and more complex the necessity to measure, monitor and control the oil or gas well in every sense becomes more important from a production optimization, safety and cost point of view.
Important parameters often required by the industry are pressure, temperature, flow rate, etc., either during drilling or after the well is completed. Electrical and fiber optic based systems can provide this information. Fiber optic systems have the advantage of being relatively immune to temperature and electromagnetic influences and are thus viewed as more reliable—especially when deployed in harsh environments. As a result, in the petroleum and gas industry, passive fiber optic sensors are often used to obtain various downhole measurements, such as, pressure or temperature. For example, a string of optical fibers within a fiber optic system may be used to communicate information from wells. In such a case, downhole measurements may be obtained from optical gauges and/or sensors such as for example Fabry-Perot sensors. Typically, a well may require 1, 2 or more gauges or sensors to measure well parameters along the full depth of the well or concentrated in certain areas.
Additionally, in more complex completions, wells often have downhole moving parts such as valves that may be opened or closed to control flow based on the information provided by the above. These devices are typically hydraulic, although electrical systems also exist. Hydraulic control systems need to be deployed in the wells on site in order to work the downhole moving parts. Hydraulic channels and fittings are typically assembled and tested just prior to insertion into the well from sections of tubing and interchangeable fittings.
When these optical, electrical and/or hydraulic systems are deployed in a well, either inside the tubing, inside the annulus or outside the casing, these systems need to be protected from the harsh well environment. This protection is typically achieved by encasing the fiber optic, electrical conductor or hydraulic channel in a hermetic cable. The complexity and precise configuration of this cable will depend on the specific needs associated with the particular well. In the case of hydraulic lines, the cable is essentially a tube. However, in the case of electrical, optical, or hybrid cables the internal configurations of the hermetic cable may be very complex containing multiple fibers and/or electrical conductors.
When deploying sensors or hydraulic systems in a well, the system is typically built onsite just prior to insertion into the well so that the system may be customized to the needs of the well. To build these custom systems, the hermetic cable(s) are cut so that the appropriate sensors or hydraulic components may be added to the systems. When joined, the performance and integrity of the joint needs to mirror the performance and integrity of the original cable in terms of transmissivity and protection against the harsh well environment.
The joining of cable-to-cable or cable-to-gauge is often achieved by means of a splice. These points of attachment are susceptible to the extreme pressure, temperature, and chemical environmental conditions within a well. Therefore, the splice needs to be configured such that the hermetic nature of the cable may be re-established. This also means the seals used need to be testable for sealing integrity.
In addition, during deployment, accidental severing of the cable(s) may sometimes occur. To minimize delays in deployment the splice needs to be relatively simple and quick to complete in an oil field environment before deployment. Such splices may also be configured to act as wellhead feedthroughs, packer penetrators, and safety valve penetrators as identified by the well completion.
Therefore, a need exists in the art for a splice that can be deployed quickly. Furthermore, a need exists to be able to test the integrity of the splice prior to exposure to extreme conditions.